The present invention relates generally to telecommunications devices and, more particularly, to devices for composing messages to be transmitted by telecommunications devices.
Telecommunications devices, such as radiotelephones, have become increasingly popular for both personal and commercial use. Radiotelephones generally refer to communications terminals which provide a wireless communications link to one or more other communications terminals. Radiotelephones may be used in a variety of different applications, including cellular telephone, land-mobile (e.g., police and fire departments), and satellite communications systems. With their increase in popularity, radiotelephones have been undergoing miniaturization to facilitate storage and portability. Indeed, some contemporary radiotelephone models are only 9-12 centimeters in length.
SMS (Short Message Service) is a service for sending messages to and between telecommunications devices, such as radiotelephones, that use Global System for Mobile (GSM) communication. SMS messages are typically transmitted to a telecommunications device within the same cell or to a telecommunications device with roaming capability. However, SMS messages may not require a mobile telecommunications device to be active and within range. Furthermore, SMS messages may be held for a length of time until a mobile telecommunications device is active and within range.
SMS messages are conventionally composed using the keypad of a telecommunications device, such as a radiotelephone. Unfortunately, composing SMS messages with conventional keypads of radiotelephones may be difficult because of the limited number of keys (typically 18-20). Because of the limited number of keys, each key of a radiotelephone keypad typically performs multiple functions. For example, numeric key xe2x80x9c2xe2x80x9d may also represent the characters xe2x80x9cAxe2x80x9d, xe2x80x9cBxe2x80x9d and xe2x80x9cCxe2x80x9d when activated. To compose an SMS message with conventional radiotelephone keypads, a user may have to press the keys of the keypad in long, awkward sequences. For example, to select the character xe2x80x9cCxe2x80x9d, a user may have to press the xe2x80x9c2xe2x80x9d key multiple times to cycle through the possible functions of the key. Composing a simple message of just a few words may require many keystrokes. As such, composing SMS messages in this manner may be difficult and confusing to users.
In addition, as radiotelephones become smaller, less area may be available for keypads. Accordingly, keypads may also become smaller, with the size and spacing of keys decreasing. As keypads become smaller through radiotelephone miniaturization, users may find it more difficult to compose SMS messages. To accommodate radiotelephone miniaturization, it may become necessary to eliminate certain radiotelephone functions because of lack of space for keys to adequately perform these functions. Alternatively, it may be necessary to require certain keys to perform many additional functions.
Voice recognition devices may also be utilized to compose SMS messages via telecommunications devices. Unfortunately, voice recognition techniques may require enhanced memory and processor capabilities that may increase costs associated with manufacturing. Furthermore, voice recognition techniques may have limited vocabularies from which messages can be composed. Also, the use of voice recognition in public may be undesirable because of privacy concerns.
Handwriting recognition devices may also be utilized to compose SMS messages via telecommunications devices and may overcome the limited vocabulary problem associated with voice recognition devices. Unfortunately, conventional handwriting recognition devices may require high-resolution touch pads and various complex and expensive electronic components which can increase the manufacturing costs of telecommunications devices.
In view of the above, it is an object of the present invention to provide ergonomic, easy-to-use alphanumeric character input devices for composing messages, such as SMS messages, on small, handheld radiotelephones.
It is another object of the present invention to facilitate radiotelephone miniaturization efforts by providing alphanumeric character input devices for radiotelephones that need not compromise conventional keypad functionality.
It is another object of the present invention to allow simplified radiotelephone assembly and reduced manufacturing costs.
These and other objects of the present invention can be provided by input devices for use with radiotelephones, and other electronic devices, that recognize and display handwritten alphanumeric characters on a radiotelephone display. A plurality of adjacent touch switches are arranged in an array beneath an exposed touch pad. Each touch switch in the array produces a respective analog voltage signal (xe2x80x9conxe2x80x9d or xe2x80x9coffxe2x80x9d) in response to user activation of an area of the touch pad during a handwriting stroke.
An analog/digital converter receives and converts a sequence of analog voltage signals produced by a user activating one or more of the touch switches during a handwriting stroke into a sequence of digital values. A processor, working in conjunction with a handwriting recognition algorithm, processes the sequence of digital values, recognizes the alphanumeric characters that corresponds to the handwriting strokes of the user, and then displays the recognized alphanumeric characters within the radiotelephone display.
Input devices that recognize and display handwritten alphanumeric characters within a radiotelephone display according to the present invention may be located in various positions and locations on a radiotelephone housing. For example, an array of touch switches may be located on a flip cover of a radiotelephone so as to be exposed when the flip cover is in an open position. Applying pressure to the touch pad surface using a stylus or other object, including a finger, a user may form individual alphanumeric characters via conventional handwriting strokes.
Input devices according to the present invention may require less space than conventional radiotelephone keypads. Accordingly, radiotelephone miniaturization efforts can be accommodated by the present invention. Furthermore, handwriting recognition devices according to the present invention may not require enhanced memory or processor capabilities as compared with conventional high resolution touchpads which typically detect handwriting at the pixel level and, thus, may require high resolution analog/digital converters.